Method and system for preparing densified lignocellulosic pulp for use in thermoplastic composite manufacturing processes

ABSTRACT

A method of preparing lignocellulosic fibre aggregates from a densified mass of lignocellulosic fibre, such as densified bales, for use in manufacturing high performance, recyclable and moldable lignocellulosic fibre and thermoplastic composites, or articles made of the high performance, recyclable and moldable lignocellulosic fibre and thermoplastic composites is provided. The method includes: (a) feeding densified forms of lignocellulosic fibre into a size reduction device; and size reducing the lignocellulosic fibres so as to produce dense lignocellulosic fibre aggregates having an average size profile suitable for use in manufacturing high performance, recyclable and moldable lignocellulosic fibre and thermoplastic composites, or articles made of the high performance, recyclable and moldable lignocellulosic fibre and thermoplastic composites. The density of the lignocellulosic fibre is generally maintained throughout the method. A system for preparing lignocellulosic fibre in accordance with the method is also provided.

FIELD OF THE INVENTION

This application is a Divisional of U.S. application Ser. No. 12/863,316filed Jul. 16, 2010. The present invention relates generally to thefield of lignocellulosic/thermoplastic composite materials. The presentinvention more particularly relates to the field of processing,metering, and feeding densified lignocellulosic pulp into thermoplasticcomposite manufacturing processes.

BACKGROUND OF THE INVENTION

Lignocellulosic/thermoplastic composites are materials that combinethermoplastic polymers with lignocellulosic materials, which are used aseither reinforcements or fillers. The advantages of such composites axewell documented in prior art such as in Canadian Patent Application No.2,527,325 (Sain et al.).

There are numerous sources of lignocellulosic materials that may be usedas thermoplastic composite fillers or reinforcements. Such sources mayinclude both wood and non-wood based materials. Non-wood based materialsmay include bast and leaf fibres taken from agricultural crop such ashemp. flax, wheat, and sisal.

There are also various mechanically or chemically processed forms ofsupplying such lignocellulosic materials depending on the source. Suchforms include: powders or particulates including wood flour and sawdust,chopped fibres or strands, continuous rovings, woven and non-woven mats,and pulp.

Pulp fibres are generally a product of lignocellulosic materials thathave been processed through a combination of chemical and/or mechanicalpulping processes. Such processes including Kraft and Mechanical pulpingare well known within the pulp and paper industry. Althoughlignocellulosic pulp can be produced from agricultural fibre sources, byfar the largest source of pulp in the world is wood for use inpapermaking. paperboard, and absorbent products applications.

Most lignocellulosic pulps are densified and packaged into a baled form,which represents a low-cost method of storing and transporting such rawmaterials. More specifically, bales of commercially available wood pulprepresent a large and relatively reliable supply of lignocellulosicfibres for use in thermoplastic composites applications.

There are numerous conventional processes that are used to combinelignocellulosic materials with thermoplastics, most of which are wellknown to those skilled in the an of plastics processing. Such processesinclude extrusion, compounding, compression molding, injection molding,and combinations or variations thereof.

To date, the majority of conventional and commercially availablelignocellulosic-thermoplastic composites use lignocellulosic materialsthat are supplied in the form of powders such as wood flour. As such,feeding difficulties into such manufacturing processes are reduced, aspowders are better flowing than fibrous materials. The other majorcategory of conventional lignocellulosic/thermoplastic compositematerials includes compression-molded parts, however in this casefeeding issues are diminished as the fibres are typically placed into anopen mold and are supplied in various forms of mats.

The feeding of fibrous materials into plastics molding or compoundingmachines such as extruders are well-known challenges in thethermoplastic composites field. If the bulk density of the material istoo low, or if the fibre lengths are too long, “bridging” occurs.“Bridging” refers to a ease where the material does not flow, and is ineffect clogging transition points in the process, such as at the feedthroat of an extruder.

In the fields of both glass and lignocellulosic fibre reinforcedthermoplastics, numerous approaches have been used to solve problems offeeding and bridging. Many solutions to feeding fibrous materials arealso linked with other technical requirements, including mechanicalperformance.

An increased fibre length is often desired in thermoplastic compositeapplications to maximize mechanical properties. However, the flowabilityof fibrous materials decreases with increasing fibre lengths. Onesolution to ibis problem is to change the nature of the process andprovide fibrous material in the form of yarns or continuous rovings. Inthis case the rovings are “pulltruded” and subsequently cut and mixedthrough an extruder. The disadvantage of such a process is thatproducing rovings or yarns increases the raw material costs.

Barlow et al. in U.S. Pat. No. 6,743,507 (2004) describe a process inwhich lignocellulosic pulp is first converted into a densified pelletusing a water-soluble binder for ease of feeding. It requires that thefibres in sheet form be first broken into discrete bundles, which inturn are pelletized with the binder. The addition of both these stepsand the use of binding chemicals would add cost to the process. Anotherembodiment of the invention involves capturing and pelletizing the pulpat the mid before u is formed into sheets. This embodiment does notallow for the use of commercially available market pulp.

Dezutter et al. in U.S. Pat. No. 6,811,879 disclose a new form of Hakepulp having a specific size, density and wet dispersibility, that may bemetered in specified quantities when adding to cementitious products dueto the fact that bulk quantities of the flakes flow well in conduits andother enclosed containers. Dezutier et al. in U.S. Pat. No. 6,837,452further discloses a process for dewatering liquid pulp stock to producesingulated pulp Hakes. Such flakes may be sent to a baler for packaging.

Dezutter and Hansen in U.S. Pat. Nos. 7,201,825 and 7,306,846 disclose aprocess for making discrete particles of cellulosic material that areflowable and meterable. Such particles comprise singulated cellulosefibres that have been densified.

Process aids may be added to assist in the now of fibrous materials.Khavkine et al. in U.S. Pat. No. 6,883,399 (2004) incorporate a blend offlax bast fibres and skives for improved flowability. Shimada et al, inU.S. Pat. No. 5,087,518 (1992) combine a mixture of glass flakes andfibres to provide for a free-flowing reinforcing material inthermoplastic resins.

Despite the numerous sources and forms of lignocellulosic materialsavailable, and the existing techniques of feeding fibrous materials,there is a need for a process capable of supplying densifiedlignocellulosic pulps into a variety of thermoplastic compositemanufacturing processes. The process should meet the particularrequirements of such composite manufacturing processes includingsupplying pulp without any feeding difficulties, and should enableprecise control of the feed rates.

The present invention meets the aforementioned requirements and iscapable of delivering lignocellulosic pulp into composite manufacturingprocesses without any bridging effect. It allows for the use ofconventional market pulp, is readily scalable, and is capable ofintegrating directly into any thermoplastics composite manufacturingprocess, whether operating in continuous or batch modes.

SUMMARY OF THE INVENTION

In one aspect, the present disclosure relates to a method of preparingdense lignocellulosic fibre aggregates for use in manufacturing highperformance, recyclable and moldable lignocellulosic fibre andthermoplastic composites, or articles made of the high performance,recyclable and moldable lignocellulosic fibre and thermoplasticcomposites, characterized in that it comprises the steps of: feeding adensified form of lignocellulosic fibre into a size reduction device;and size reducing the densified form of lignocellulosic fibre so as toproduce dense lignocellulosic fibre aggregates having an average sizeprofile suitable for use in manufacturing high performance, recyclableand moldable lignocellulosic fibre and thermoplastic composites, orarticles made of the high performance, recyclable and moldablelignocellulosic fibre and thermoplastic composites.

In another aspect, the present disclosure relates to a system forpreparing dense lignocellulosic fibre aggregates for use inmanufacturing high performance, recyclable and moldable lignocellulosicfibre and thermoplastic composites, or articles made of the highperformance, recyclable and moldable lignocellulosic fibre andthermoplastic composites, characterized in that it comprises: a sizereduction apparatus operable to size reduce a densified form oflignocellulosic fibre so as to produce the dense lignocellulosic fibreaggregates having an average size profile suitable for use inmanufacturing high performance, recyclable and moldable lignocellulosicfibre and thermoplastic composites, or articles made of the highperformance, recyclable and moldable lignocellulosic fibre andthermoplastic composites.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of the preferred embodiments) is (are) providedherein below by way of example only and with reference to the followingdrawings, in which:

FIG. 1 illustrates a block process diagram of one embodiment of thepresent invention;

FIG. 2 illustrates a typical Bleached Kraft pulp bale;

FIG. 3 illustrates a typical flash dried High-Yield pulp bale;

FIG. 4 Illustrates an example low-speed high-torque system with verticalfeed;

FIG. 5 illustrates an example low-speed high-torque system withhorizontal feed;

FIG. 6 illustrates a cross sectional view of a screw within a tube

FIG. 7 illustrates an example loss-in-weight screw feeding system withrotor agitation;

In the drawings, one embodiment of the invention is illustrated by wayof example, it is to be expressly understood that the description anddrawings are only for the purpose of illustration and as an aid tounderstanding, and are not intended as a definition of the 20 limits ofthe invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is a method and system for producing dense fibreaggregates from a densified mass of lignocellulosic fibre, for example,a densified bale. As a skilled reader will recognize, the presentinvention may utilize other densified forms of lignocellulosic fibreother than baled pulp. It should also be understood that a “bale” inthis disclosure refers to a densified mass regardless of shape,dimension, or method of forming the bale. Dense fibre aggregates areproduced by way of a dense fibre aggregate production device wherebyaggregates of pulp are produced through gentle size-reduction of thelignocellulosic fibre. This removal occurs without any significant“defiberization effect” or reduction in density of the pulp. Also, thedense fibre aggregate production device is disposed to remove fibreaggregates with minimal shearing action on the individual fibres,thereby preserving fibre length.

The densified fibre of the present invention may be produced to provideparticular benefits for feeding into thermoplastic compositemanufacturing processes, when for example, using loss-in-weight feedsystems: (a) it provides relatively narrow particle size distribution;and (b) exhibits reduced “bridging” at feeding and transition pointsduring the composite manufacturing process. Such properties are alsobeneficial for feeding into processes following size reduction andpreceding thermoplastic composite manufacturing processes (“interveningprocesses”).

In another aspect of the invention, the density of the fibre issubstantially maintained during any intervening processes. Accordingly,the densified fibre yielded by the method and system of the presentinvention may be stored, conveyed or fed through systems and processesprior to any composite manufacturing process. The density of thelignocellulosic fibres is maintained throughout the method and processwhereby the dense fibre aggregates can provide individual panicledensities approximately equal to, or substantially the same as, thedensity of the lignocellulosic fibre in the originally supplieddensified form

A first aspect of the present invention involves a method of preparingdensified lignocellulosic fibre aggregates from lignocellulosic fibrewhich includes obtaining the densified mass of lignocellulosic fibrefrom a related process for forming the densified mass of lignocellulosicfibre. A second aspect of the present invention, involves a method ofpreparing densified lignocellulosic fibre aggregates fromlignocellulosic fibre obtained in a densified bale form.

The use of baled lignocellulosic pulp in thermoplastic composites is anunconventional application in an industry that is designed to servicepapermaking and absorbent products manufacturers. The two key issues tobe addressed when using baled lignocellulosic pulp for compositesapplications are the conversion of the pulp bales into a suitable formthat can be subsequently fed into any conventional thermoplasticcomposites manufacturing process, and the precise feeding of such pulpinto the manufacturing process. The overall method is illustrated havingregard to FIG. 1.

Because papermaking is the primary application of pulp bales, there istypically no need for dry processing as the entire bale is thrown into atank of water or “hydra-pulper”. Thermoplastic composite manufacturingprocesses on the other hand, require pulp with low moisture content. Assuch, for composites manufacturing the advantage of using water tobreak, apart or dissolve the bales is lost.

For absorbent product applications, the pulp bales are typicallyprocessed dry. The difference is that a low bulk density “defiberized”form of the pulp is required, which in thermoplastic compositeapplications would cause the bridging effect during feeding.

For the purposes of this invention, “lignocellulosic pulp” is defined asany lignocellulosic fibrous material that has been manufactured usingeither chemical or mechanical pulping processes or combinations of both.Such processes include: the Kraft process. Sulphite processes, or thefamily of High-Yield pulping processes. Some examples of High-Yieldpulping processes include: Thermomechanical pulps (TMP),Chemithermomechanical pulp (CTMP), and Bleached Chemithermomechanicalpulps (BCTMP). The pulp can be from both wood and non-wood sources suchas agricultural fibres as well as both virgin and recycled fibres. Itshould be noted that while lignocellulosic fibres in pulp form arepreferred in the present invention, other forms of lignocellulosicfibres such as those exposed to enzymatic treatments may also beprocessed.

The bale density referred to in this embodiment should usually definethe theoretical maximum density of material eventually fed into thedownstream thermoplastic composites manufacturing process. This baledensity may be controlled during sheet forming or compression of thebales, depending on the pulping process.

The largest source of lignocellulosic pulp is from commerciallyavailable wood pulps such as Bleached Kraft pulps or High-Yield pulps.Commercially available Bleached Kraft pulp bales typically consist ofindividual sheets of pulp that have been dried and stacked to form acomplete bale as depicted in FIG. 2, whereas High Yield pulp balestypically consist of a homogenous mass of pulp that has been flash driedand pressed in molds into individual blocks or “cookies”. The “cookies”are then typically stacked four-high to form a complete bale as depictedin FIG. 3. Kraft pulp bales typically weigh 500-600 lbs with densitiesbetween 0.8-1.1 g/cm³, while flash-dried bales of Chemithermomechanicalpulp weigh between 300-500 lbs and have densities between 0.5-0.9 g/cm³.Both types of bales are shipped “dry”, meaning approximate bone-drymoisture content of between 10-16%.

When provided with lignocellulosic pulp bales, there have been prior artmethods have attempted to size-reduce such bales for other applicationssuch as sanitary napkins and diaper manufacturing. Examples of suchmethods may include cutting or splitting the bale into sheets or slabs,as well as exposing the bale to various forms of high-impact orhigh-speed milling or grinding, such as hammermills. Such processeshowever, do not produce forms of the pulp that are suitable forthermoplastic composites manufacturing processes.

When exposing the bales to various forms of high-impact or high-speedgrinding, the bulk density of the pulp is drastically reduced, and largeamounts of dust are produced. Pulp converted through such processes isextremely difficult to feed due to its low bulk density form.

The present invention uses an alternative strategy tor convertinglignocellulosic pulp bales into a form suitable for feeding. Instead ofusing the previously described techniques, the present invention iscapable of directly converting the bales through, the production of“Dense Fibre Aggregates” from the bale surfaces. This is done withoutany prior modifications or processing conducted on the bale. Such densefibre aggregates are suitable for controlled feeding into a variety ofthermoplastic composite manufacturing processes. The present inventionalso maximizes retention of fibre length and minimizes production ofdust.

Dense fibre aggregates are defined as particles of approximately 0.2-3.0inch in width, more preferably 0.5-1.0 inch in width, and withindividual aggregate densities that are close to the pre-converteddensity of the pulp bale. Such aggregates may be in a variety of shapessuch as oval, rectangular, cubic, or discs. In the case of oval orcircular shaped aggregates “width” is defined as the diameter, while forirregular or rectangular shaped aggregates, “width” is defined as thelonger of the two cross sectional dimensions. Depending on the pulpsource and type of bale, the aggregates may also have varying thickness.For example, when taken from Kraft pulp the aggregates would have alower thickness (flake form) than from flash-dried high-yield pulpbales.

Typically the individual aggregate densities will be higher than thebulk density, as the latter is determined by how the individualaggregates pack together, and a densified bale represents approximatelythe highest packing density. The dense fibre aggregate bulk densitiesare typically between 0.1-0.8 g/cm³. Preferably, densities of theindividual aggregates are equal to the original bale density. The densefibre aggregates produced by the present invention may have a narrowparticle size distribution, and may not experience “bridging” at feedingand transition points during the process so long as their density isapproximately maintained. Due to their narrow size distribution,controlled and even feed rates may be achieved.

FIG. 1 illustrates a block diagram of one particular embodiment of thepresent invention. A lignocellulosic pulp bale 20 is fed into a densefibre aggregate production device 21. The bale may be fed using anystandard conveying means, such as a belt conveyor. In one embodiment ofthe present invention, the dense fibre aggregate production device is amachine equipped with one or more shafts or “rotors” rotating at a“low-speed”, where each rotor has a series of cutters or protrusions.The bale is pressed against the low-speed rotors in order to produce thedense fibre aggregates. By operating the rotors at tow-speed, the denseaggregates of pulp may be gently removed directly from the bale surfaceby the cutters without any significant “defiberization effect” orreduction in density of the pulp. The cutters remove fibre aggregatesfrom the surface of the bale without imposing any severe shearing actionon the individual fibres, therefore fibre length may also be wellpreserved.

One example of such a dense fibre aggregate production device is alow-speed high-torque shredder FIG. 4 and FIG. 5 equipped with a screen50 and with one or more rotors 51, each rotor comprising protrusions,blades or cutters at defined spacings. Such shredders are commerciallyavailable from companies such as SSI Shredding Systems. Devices of thistype may operate either vertically or horizontally, meaning that thebale is placed on top of the rotors in the vertical case FIG. 4, or thebale is pressed horizontally against the rotors FIG. 5.

It is important to note that while there are numerous size-reductiondevices that operate on the principle of cutting or shearing rotors, thediscussed embodiment of the present invention requires operation atlow-speed and high-torque, “Low-speed” refers to machines operating atrotations per minute (RPM) preferably below 150 RPM, more preferablybelow 90 RPM, although RPM settings chosen and actual results may dependon other factors such as the dimensions of the cutters and diameter ofthe rotor. In general, low-speed high-torque operation differs from sizereduction processes mat appear to be similar such as granulators orhammer mills, which operate at or above several hundred RPM. Due to thelower RPM at operation, an increased torque must be maintained whencompared to typical granulators in order to extract the denseaggregates.

The differences when operating at low-speed and high-torque compared tosimilarly configured devices operating at a higher RPM are apparent whenexamining the converted product, as the density of the pulp is wellpreserved when the RPM is maintained at a low level and the denseaggregates are produced. Increasing RPM will lead to a drastic decreasein bulk density, and instead of dense aggregates a fluffy form of thepulp is produced. For example, a typical pulp bale at bale density of0.6 g/cm³ may be reduced to a bulk density of 0.02 g/cm³ if processed atRPMs over 150. Such low densities cause severe bridging and feedingdifficulties. Increasing RPM also leads to an increased production ofdust.

Depending on the scale of the compounding or molding process 24, avariety of mass throughputs at dense fibre aggregate production 21 maybe required, in addition, pulp bales may be supplied in a variety ofdimensions. The number and configuration of the rotors may affect boththe throughput and bale handling capability of the aggregate productionsystem. For example a four-rotor system may be capable of handlinglarger bales, and/or have higher throughput than a single rotor system.The size and number of rotors of the aggregate production systemhowever, are simply a function of scale and not necessarily a primaryelement of the principle of the present invention.

The combination of process variables such as: pulp bale type, startingbale density, screen size/shape, and cutter shape/spacings will definethe final size and shape of the dense fibre aggregates, which is matchedto the throughput and size of the feeding step 23 as well as theresulting composite manufacturing process being fed 24. A narrow andcontrollable aggregate size distribution is maintained through theadjustment of such variables.

In order to maintain sufficient pressure of the bale against the rotorsfor dense fibre aggregate production to occur, it is desirable to useeither the weight of additional bales which are fed continuously on topof the current bale being processed, or to use a device such as a “ram”to maintain pressure as the weight of the bale decreases while theaggregates are being produced. A ram is a device that applies pressureonto the bale against the rotor, and is often powered through ahydraulic system. Such a device may apply pressure downward in the caseof a vertically fed size reduction system, as shown in FIG. 4, orhorizontally in the ease of a horizontal system, as shown in FIG. 5. Ifsufficient pressure is not maintained, the bale may “float” on top ofthe rotors and production of dense fibre aggregates may not occur.

Following the production of dense fibre aggregates, it is important thatthe density of the aggregates be substantially maintained up to thepoint of entry into the composite manufacturing process 24. Drasticreduction in density may lead to bridging problems at subsequent feedingor handling steps. The dense fibre aggregates are conveyed 22 either totemporary storage, or directly to a feeding system 23. Optionally, thedense fibre aggregates may also be conveyed to a dryer for moisturecontent reduction before further feeding into the compositesmanufacturing process. If the dense fibre aggregates are temporarilystored or dried before feeding, a secondary feeding and conveying systemoperating on similar constraints discussed should be used.

Thus any number of systems and related processes including storage,conveying, or feeding, occurring in between the steps of size reduction21 and the composites manufacturing process 24 should be provided suchthat there is minimal reduction in pulp density.

The final step of the present invention involves feeding 23 the densefibre aggregates into typical equipment used in thermoplastic compositemanufacturing processes 24. Such processes may include extrusion (forexample single or twin-screw extrusion), compounding, injection molding,or combinations thereof, such as in-line compounding arid injectionmolding systems. Typically, equipment used in such manufacturingprocesses have feed throats with associated hoppers mounted on top. Theaggregates are fed into the hopper and are discharged by gravitydownwards into a rotating screw, in order for the aggregates to properlyflow from the hopper into a screw, the density must again be maintainedduring the feeding step 23 to prevent “bridging” at the throat of theequipment used for composite manufacturing. The feeding step must alsoallow for precise control of feed rates in order to determine the exactmass flow rate of aggregates being fed either in continuous or batchprocessing.

In one embodiment of the present invention, the dense fibre aggregatesare fed using at least one rotating screw, more preferably a spiralscrew, however any screw that does not cause reduction in density of theaggregates may be used. The screw is typically mounted within a tube ofapproximately the same length. A spiral screw is preferred because itsopen spiral design allows aggregates to be conveyed without muchreduction in density and the aggregates will not “pack” within theflights of the screws. In addition, depending on the compositesmanufacturing process, multiple feed screws may also be used.

FIG. 6 depicts a cross section of a screw 70 within a tube 71. It isimportant to note that the distance “D” between the screw outer diameteredge and the inner wall of the tube must be selected to prevent anyshearing of the aggregates between the screw and the tube wail whichcould cause a lowering of the aggregate bulk density, and subsequentbridging of the aggregates. If the distance “D” is too small, theaggregates will be defiberized, yet if the distance “D” is too large,improper filling of the screw will occur and the material will not feedor feed rates will be lowered. Thus, a spiral screw sized correctly inrelation to the tube inner diameter may be capable of conveying thedense aggregates without causing any bridging effect. The optimaldistance “D” depends on the size of the aggregates being fed, however itis approximately equal to the maximum diameter or length of theaggregates.

FIG. 7 shows a side-view of a typical loss-in-weight screw feeder withessential components, Such a feeder is equipped with the described screwand tube 61 along with a hopper 64, and a load cell 62 connected tomotor and system controls 63. In a loss-in-weight feeder, the feed rateis controlled using the load-cell and system controls to track thereduction in weight of the dense aggregates within the hopper. As thefeed rates are typically controlled by screw speed, this allows fordynamically adjustable feed rates by constantly varying screw speed withthe rate in weight reduction. When the hopper is at a low-level ofaggregates remaining, the system is re-fed while the feeder temporarilyruns in “volumetric mode”.

Under certain circumstances, such as when using feeder hoppers withdimensions that are not favorable for material flow, an embodiment offire present invention may utilize a screw feeder with agitation. Forthe purpose of this invention, agitation is defined as a mechanism thatcontinuously maintains the bulk of the dense aggregates within thefeeder's hopper in motion. One example of agitation is a set of rotating“arms” 60, such as those shown in FIG. 6. It may be important to ensurethat the agitation mechanism does not reduce density of the aggregateswhile they reside in the feeder's hopper. Other forms of agitation suchas vibrating hopper walls may also he used.

EXAMPLE 1

In order to produce dense fibre aggregates from a lignocellulosic pulpbale, a thermomechanical pulp bale with an approximate bale density of0.8 g/cm³, dimensions of 60 cm×80 cm×54 cm, and bone-dry moisturecontent under 15% was fed into a Q100 Low-Speed High-Torque Shreddermanufactured by SSI Shredding Systems Inc., a company having its placeof business in Wilsonville, Oreg., USA. The system was equipped with a2-inch cutter and a 1.5-inch screen and was running at approximately 30RPM. The Q100 system consists of 4 rotors and has a rated horsepower of250-300 hp. Dense fibre aggregate production was performed without theoptional hydraulic ram, and additional bales were continuously fed ontop to maintain downward pressure. If bales were not led to maintaincontinuous pressure, the bale currently being processed “floated” on topof the rotors once its weight had been reduced. The resulting densefibre aggregates produced were of individual densities close to that ofthe original bale density, and had a bulk density of approximately 0.5g/cm³.

Following production, the dense fibre aggregates were transferredwithout any change in their density into the extension hopper of aDSR-Series loss-in-weight screw feeder manufactured by BrabenderTechnologic, a company having its offices in Mississauga, Ontario,Canada. The screw feeder was equipped with a spiral screw and anagitation mechanism using a rotor within the hopper. The extensionhopper selected for the feeder was rectangular and straight-walled tofurther minimize any bridging effect. The aggregates were fed withoutany bridging, and sufficiently filled the screw. Both batch andcontinuous feed modes were performed, and feed rates were achieved thatmatched the rated volumetric throughput of the feeder.

What is claimed is:
 1. A system for preparing dense lignocellulosicfibre aggregates for use in manufacturing high performance, recyclableand moldable lignocellulosic fibre and thermoplastic composites, orarticles made of the high performance, recyclable and moldablelignocellulosic fibre and thermoplastic composites, characterized inthat the system comprises: a) a size reduction apparatus operable tosize reduce a densified mass of lignocellulosic fibre so as to producedense lignocellulosic fibre aggregates having for use in manufacturinghigh performance, recyclable and moldable lignocellulosic fibre andthermoplastic composites, or articles made of the high performance,recyclable and moldable lignocellulosic fibre and thermoplasticcomposites, wherein the dense lignocellulosic fibre aggregates haveindividual panicle densities equal or virtually equal to the densifiedmass of lignocellulosic fibres density prior to being fed into the sizereduction device.
 2. The system of claim 1 characterized in that thesize reduction apparatus is operable to produce the denselignocellulosic fibre aggregates having an individual aggregate densityapproximately equal to the density of the densified mass oflignocellulosic fibre.
 3. The system of claim 2 characterized in thatthe size reduction apparatus includes ax least one rotor.
 4. The systemof claim 3 characterized in that the rotor is operable at low RPM and athigh torque, whereby the densified mass of lignocellulosic fibre is sizereduced through contact with the rotor.
 5. The system of claim 1characterized in that the size reduction apparatus is operable at lowRPM and with high torque.
 6. The system of claim 1 characterized in thatthe size reduction apparatus is a low-speed high torque shredderequipped with at least one rotor.
 7. The system of claim 6 characterizedin that the least one rotor is operable to rotate at speeds betweenabout 1 and 100 RPM.
 8. The system of claim 1 characterized in that thesize reduction apparatus is operable to produce the denselignocellulosic fibre aggregates having a generally predetermined size.9. The system of claim 1 characterized in that the size reductionapparatus is operable to produce the dense lignocellulosic fibreaggregates having a narrow aggregate size distribution with minimaldegradation in fibre length.
 10. The system of claim 1 characterized inthat the size reduction apparatus is operable to produce the denselignocellulosic fibre aggregates having reduced bridging for feedinginto a manufacturing process resulting in manufacture of highperformance, recyclable and moldable lignocellulosic fibre andthermoplastic composites, or articles made of the high performance,recyclable and moldable lignocellulosic fibre and thermoplasticcomposites.
 11. The system of claim 1 characterized in that the sizereduction apparatus is operably linked to one or more apparatuses foruse in manufacturing lignocellulosic fibre and thermoplastic compositesor products comprising lignocellulosic fibre and thermoplasticcomposites being operable to perform one or more of the following: a)extrusion; b) compounding: c) batch mixing; d) injection-molding; and e)in-line compounding and injection-molding apparatus whereby the denselignocellulosic fibre aggregates are fed at a predetermined mass Howrate into the said one or more apparatuses.
 12. The system of claim 11characterized in that the one or more apparatuses include at least onerotating screw, whereby the dense fibre aggregates may be fed at thepredetermined mass flow rate into the said one or more apparatuses. 13.The system of claim 12 characterized in that the one or more apparatusesinclude a a loss-in-weight screw feeder, whereby the dense fibreaggregates may be fed at the predetermined mass flow rate into the saidone or more apparatuses.
 14. The system of claim 13 characterized inthat the loss-in-weight screw feeder has at least one spiral screw. 15.The system of claim 13 characterized in that the loss-in-weight screwfeeder includes or is linked to an agitation mechanism.
 16. The systemof claim 1 characterized in that the size reduction apparatus includes alow-speed high-torque shredder equipped with one or more rotors and ascreen.
 17. The system of claim 1 characterized in that the sizereduction apparatus is operable to produce the dense lignocellulosicfibre aggregates having an approximate bulk density of between 0.1 and1.5 g/cm³.
 18. The system of claim 1 characterized in that the sizereduction apparatus is operable to produce the dense lignocellulosicfibre aggregates having an average width of between 0.2 and 3 inches.19. The method as claimed in claim 1 characterized in that the densifiedmass of lignocellulosic fibre is in densified bale form.
 20. The systemas claimed in claim 1 characterized in that the densified mass oflignocellulosic fibre is in densified bale form.